Answer:
I think that it should be

Step-by-step explanation:
Here,
we take , a - b = A,b-c = B , c - a= C
A+B+C = 0
we know that,

Here , A+B+C = 0
so,
A^3 +B^3 + C^3 = 3 ABC
now we put the values

I am done .
Answer:
my bad it was a mistake .
Step-by-step explanation:
Yes ding ding ding ding ding ding
Is there any other information?
Answer:
(a) 7 essays and 29 multiple questions
(b) Your friend is incorrect
Step-by-step explanation:
Represent multiple choice with M and essay with E.
So:
--- Number of questions
--- Points
Solving (a): Number of question of each type.
Make E the subject of formula in 

Substitute 36 - M for E in 


Collect Like Terms


Divide both sides by -4


Substitute 29 for M in 


Solving (b): Can the multiple questions worth 4 points each?
It is not possible.
See explanation.
If multiple question worth 4 points each, then
would be:

Where x represents the number of points for essay questions.
Substitute 7 for E and 29 for M.


Subtract 116 from both sides



Make x the subject

Since the essay question can not have worth negative points.
Then, it is impossible to have the multiple questions worth 4 points
<em>Your friend is incorrect.</em>